The long-term objective is to elucidate the mechanism by which Bordetella avium (previously classified as Alcaligenes faecalis) causes rhinotracheitis in turkeys and to establish the means by which genes encoding colonization and virulence antigens are regulated in vitro and in response to the avian host. The specific objectives of the work proposed in this application are as follows: (1) to identify which of the outer membrane proteins, hemagglutinins, and/or pili are important in the colonization of B. avium in the upper respiratory tract of birds; (2) to determine the role and structure of the dermonecrotic toxin of B avium; (3) identify regulatory gene(s) of B avium and study the regulation of surface proteins and dermonecrotic toxin by these gene(s); and (4) to investigate the regulation of genes for colonization and virulence in response to the avian host. Once genes for B avium colonization antigens and dermonecrotic genes of B pertussis. A diversity of recombinant DNA techniques and microbial genetics procedures will be used to identify and characterize genes and gene products specifying colonization and virulence antigens. The studies will make use of the technologies of biochemistry, immunology, and microscopy and will employ cell and organ culture systems. In addition, these investigations will use newly hatched turkeys to investigate colonization, virulence, and the regulation of genes specifying these traits in the intact animal.